Radiophone



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APPLICATION FILED OCT. 8.19l9.

Patented July 6, 1920.

I4 Re c eivi'ng .Devices F29 Fg-3 22 v PATENT OFFICE.

WILLIAM-W. COBLENTZ, OF WASHINGTON, DISTRICT 0F COLUMBIA.

RADIOPHONE.

Specification of Letters Patent.

. Patented July 6, 1920.

` Application filed October 8, 1919. Serial N o. 329,365.

(FILED UNDER. -THE ACT 0F MARCH'. 3, 1883, 22 STAT. L., 625.)

To all whom t may concern: Be it known that I, WILLIAM W. C'o- BLENTZ, a citizen of the United States, re-

, siding at Washington, inthe-.District- 0f Columbia, have invented certain newl and useful Improvements in Radiophones, of which the following is a specification.

This application is made under the act of March 3, 1883, chapter 143, (U. S. Statute XXII,y page 625), and the invention hereindescribed and claimed may be \used,

by the Government of the United States, or

any of its officers or employees in the prose- 1 cution of Work for the United States, or by l any person inthe United States without the payment of any royalty thereon.

The object of my linvention is to provide a device whereby thermal radiant energy, especially infra-red or so-called heat rays, may be utilized as a means'ofcommunication.

Another object of my invention is to provide a means of varying the strength ofl the current in a charged electrical conductorby exposing my device to 'heat and light rays.

A further object of my invention is to provide an instrument of this vnature which, although it is compact in form and rigid in construction, will be lso sensitive to heat rays that it may be used to advantage in l the most refined physical experiments.

It is well known that when selenium is exposed to light rays, its electrical conductivity is greatly increased; and this property has been utilized in a great many inventions. Such a .substance is said to be photoelectrically sensitive. In theA case of selenium, its sensitivity is confined practically tothe visible rays. Moreover, its temperature co-efficient of resistance is negative so that a rise in temperature caused by absorption of radiant energy has the same' effect as that produced by light rays in` Vchanging the electrical resistance. V

I have found that the mineral, molybdenite, which is a sulfid of molybdenum (MoS2) is very sensitive photoelectrically, so that its resistance is greatly decreased on exposure to radiant energy, especially when exposed to infra-red rays. In this respect, it differs greatly from selenium. Further,

its temperature coefficient of electrical resistance is negative so that the rise in temperature which results when it is exposed to heat rays also. tends to decrease the electrical resistance. Unlike selenium, the photoelectric action 1s quick in its response. Furthermore, I have found that the thin lamina of this substance can be soldered directly to copper wires by means of ordinary solder which insures good Contact, thus eliminating the noise in the telephone which results from the fluctuations of the electric current caused by poor contacts betweenthe photosensitive mineral and the metal electrodes. A further useful physical property which I have found is that the photoelectric effect produced fis an additive phenomenon, directly proportional to the area exposed. For example, maintaining the same electric current through the receivers, if the area of the; receiving surface be doubled, the photoelectric current produced is doubled when the receiver is exposed to radiation. The

` utilization of this additive property enyby means of a galvanometer, telephone or other suitable indicating device in the circuit.

VA The photoelectric current may be amplied by means of an audion amplifier or by other well known devices recently invented.

Other objects of vthis invention will be apparent from the detailed description and from the drawings, in which- Figure l represents diagrammatically an arrangement including` my device, and suitable' well known auxiliary apparatus which .may be used in signaling, orfor detecting.

the passage of a movable object between two given points.

Fig. 2 is a top plan view of one form of the receiving device of my invention.

Figs. 3 and 4 are sectional views taken on the lines 3 3 and 4-4 respectively of the embodiment illustrated in Fig. '21

Fig. 5 is a top plan view of a modified form of receiving device; and y Fig. 6 is a sectionall view taken on the line 6.*6 of Fig. 5.

Similar reference characters refer to similar parts in all these figures.

Referring to Fig. 1, A represents a transmitting station consisting of a projector or reflector 2 containing any suitable source 1 of radiant energy, e. g., a concentrated lilament tungsten lamp or a carbon are lamp supplied through switches 15 and 4 from a suitable source of energy as a source of direct current 20, or of alternating current 3. The arc lamp may be combined with suitable inductance and capacity to produce the so-called audible or speaking arc (see, for example, the patent to Hayes and Cram, No. 654,630, dated July 3l, 1900), or a manometric flame may be used. If it is desired to employ invisible infra-red rays for secret signaling or for detecting the passage of a movable object across the path of' an invisible beam of rays, the front of the refiector 1 is covered by means of a suitable screen 5 which absorbs the visible rays and transmits the invisible infra-red rays, e. g., a deep ruby glass, or a gelatin film containing a suitable dye or asphaltum varnish.

At the receiving station, B, a suitable mirror 7 is used to concentrate the proj ected radiant energy upon the receiving device or detector 8 of myinvention. This detector is connected in circuit with an adjustable resistance 10, electric battery 9, and a suitable current indicator 22, or a suitable relay 12, or an amplierl 17. Although any suitable amplifier may be used, I have here shown one of the thermionic type, having its input circuit coupled to the circuit of receiver 8 by a coupling coil 18 and lits output circuit coupled to a pair of telephone receivers 19 by a coupling coil 16. The relay 12 may control a local circuit containing a receiving device or an indicator 13 which is energized when no radiant energy falls on detector 8, or may control a local circuit containing a device 14 which is energized when radiant energy falls on detector 8, or as shown, the relay 12 may have two sets of contacts and control both devices 13 and 14.

If' the intensity of the source of radiation, 1, fiuctuates periodically with a frequency within the range of audibility, for example, by using a hissing or speaking7.a1c, or by using an alternating current to supply the source 1, the current through the receiver 8 will vary as a result of the fiuctuation in intensity of the incident radiant energy, and a musical note of the same frequency will be produced in the telephone receivers 19. Such musical note may also be produced, when the source 1 does not fluctuate in intensity, by interposing at any point in the path of the projected beam of radiant'energy a rotating sectored disk 11, but because such a disk as ordinarily used Will obstruct half of the rays, thus reducing the sensitivity by one half, it is desirable to vary the intensity at the transmitting station in the manner first described.

The system thus far described may be used for the transmission of signals by code by emitting long and short pulses o f radiant energy, each of which will actuate the device 14 or the receiver 19, as desired. The emission at the transmitting station A may be controlled by the switch or key 4, or the source 1 may radiate continuously and the effective emission be controlled by interposing an opaque object, as 6, in the path of the emitted rays. This latter method of control immediately suggests the use of the system to detect the passage of an object between the stations A and B across the line joining them. If radiant energy is passing from A to B and an opaque object 6, as a ship, the periscope of a submarine or any other object, comes into the path of the projected rays, they are cut off and the indicator 13 will be actuated, as is obvious, or if the beam of radiant energy'is fluctuating periodically, the indicator 13 will be actuated, or the musical note in the receiver 19 will cease so long as the opaque object remains in the path of the projected rays. As invisible infra-red rays may be used, this communication, or detection, may be carried on in secret.

Referring to Figs. 2, 3 and 4 which show in detail the construction of one form of the receiving device or detector 8 of Fig. l, 21 is .a support of any suitable insulating material; 22 are metal posts secured in this material; suitable conducting leads or Wires, e. g., copper, 25, are soldered to these posts 22; the thin laminae (say 0.15 mm. in thickness) of molybdenite 23 are soldered directly to the Wires 25; and the lead Wires 26 and 27 `complete the circuit. It is, of course, to be understood that in building up a receiving surface from individual laminae of molybdenite, the number of pieces in a rovv and the number of rows (units) will be determined by the size of the material available and the surface required to obtain the sensitivity desired.

Furthermore, the manner of connecting these units, whether in series or in parallel, Will be determined by thevnature of the application of the device in "practice, in connection with the auxiliary receiving apparatus to be employed in a given case.

4Although I have mentioned that thin laminae 23 of molybdenite are used, this is not necessary, as thick pieces of material can also be use Figs. 3 and 4 are side and end view sections of the device shown in Fig. 2, showing a suitable mirror 24 for reflecting back any the molybdenite;

Fig. 5 is a top view of a modified form of i the receiving device 8 of Fig. 1, in which the top insulating support 28 is perforated by an opening 33 of sufficient size to expose the sensitive receiving surface 31, composed of a plurality of laminee of molybdenite, to the.

incident radiations.

Fig. 6, which is a sectional view of Fig. 5,

. shows the complete embodiment of my invention, assembled as it would be used to 'best advantage in actual practice so as to .utilize to the maximum eiiiciency allthe radiation falling upon the receiver. In this form, the construction of the parts 21, 22, 23, 24, 25, 26 and 27 is identical with that of the parts designated by the same numerals in Figs. 2, 3 and 4. In the form shown in Figs. 5- and 6, a second sensitive surface 31, of laminae of molybdenite, is placed in front of the sensitive surface 23. The laminae 3l are soldered to leads 30, which are in turn soldered to posts 29 secured in the insulating top 28, which has an opening 33 to allow the radiant energy to fall on the sensitive surface 31. The member 28 is held spaced from the support 21 4by suitable sides 32. In this form of receiver, the radiant energy which is transmitted by the layer 31 is available` to affect the layer 23, and if the layer 23 transmits any energy, it is reected by the mirror 24, so lthat this form of receiving de- 4 vice utilizes to the maximum eciency all the incident radiation.

In the description of this invention, I have mentioned molybdenite as 'the lactive agent in causing a change (decrease) in electrical resistance in the circuit becausev it is the most active substance yet found. I have obtained good results by using gold leaf mounted in exactly the samemanner as the molybdenite. The front surface of the gold leaf was smoked to absorb the incident radiations. Gold leafv is not sensitive photoelectrically, so that the change (increase) in electrical resistance in the circuit is due to the rise in temperature of the gold leaf caused by absorption of radiant energy. AIts heat capacity is so smallthat the amplitude of the temperature (hence, resistance and electric current) change is sufficient to produce an audible sound in the telephone.

In some cases, it may be found desirable to inclose the photo-sensitive cell 8 in acasing having a suitable aperture transparent Vtogthe radiations to be detected, so that the.

whole cell may be lmaintained at a suitable low temperature by any well known means.

Having thus described my invention, I claim: l .lf

1. A resistance unit variable by he action of radiant energy comprising molybdenite. 2. A resistance unit comprising two spacedv metallic leads and a material whose resistance is changed by the action of radlant energy bridging the space between said leads and solderedthereto.

Search 30cm* 3. A resistance unit variable by the action 1 of radiant energy comprising a body of molybdenite and metallic leads soldered thereto.

4. A resistance unit comprising a material whose resistance is variable by the action of radiant energy and circuit leads therefor, said material being capable of being soldered directly to said leads, whereby the contact resistance between said leads and said material is rendered constant.

5. A resistance unit for controlling the flow of electric current in the input circuit of a thermionic amplifier `comprising molyb.

denite.

6. In a radiaphone, a thermio-nic amplifier having input and output circuits, and means inductively coupled-to said input circuit for varying the current in said input circuit by vthe action of infra-red thermal radiation.

7. In combination, a thermionic ampliiier having input and oiitput circuits, and means associated with said input circuit for varying the current in said input circuit by the action of infra-red thermal radiation, said means comprising molybdenite.

8. Means for detecting the passage of a mbvable object between two points comprising a source for providing an invisible beam of infra-red radiations located at one of said points, and a receiving device responsive to said radiations located at the other of said points, whereby upon. interruption Qf-said radiations .by said object, said receiving device will indicate the presence of said object. p

9. Means for detecting the passage of a movable object between two points as set forth in claim 8 in which'the intensity of the beam of infra-red 'radiations is periodically varied with a frequency within-the range of audibility, so that a musical note is produced in a telephone receiver associated with the receiving device.

10. A device forl varying the current in an electrical circuit comprising two spaced layers of material sensitive to radiant energy.

11. A device for varying the current in an electrical lcircuit comprising two spaced layers of material sensitive to radiant energy,.one of said layerscomprising.molybdenite.

12. A device for controlling the current in an electrical circuit comprising two spaced layers of molybdenite.

13. A device for varying the current in an electrical circuit comprising a layer of material sensitive to radiant energy and a mirror behind said layer for reflecting back o said layer the energy transmitted by said ayer.

14. A device for controlling the current in an electrical circuit comprising a layer of molybdenite, and a mirror spaced `from said layer.

15. A device for varying the current in an electrical circuit comprising two spaced layers of material sensitive to radiant energy and a mirror spaced from one of said layers.

.16. A device for .Varyingthe current in an electrical circuit comprising two spaced layers 'of material sensitive to radiant energy, one of ,said layers comprising molybdenite, and a mirror spaced from both of said la ers. I

17. device for controlling the current inV an electrical circuit comprising two spaced layers of molybdenite, and a mirror spaced from both of said layers.

18. In a resistance unit variable bythe action of radiant energy, an insulating support, posts mounted in said support, spaced conducting leads soldered to said posts, and material whose resistance is changed by the action of radiant energy soldered between said leads.

19.` In a resistance unit variable by the action of radiant energy, an insulating support, posts mounted in said support, spaced conducting leads soldered to said posts, and inolybdenite soldered between' said leads.

20. A current controlling unit variable by .the action of infra-red radiations including a photoelectrically sensitive surface of molybdenite, said surface comprising a plurality of laminae soldered to copper leads.

21. In a device for detecting the presence of infra-red radiations, an element comprising a layer 'of molybdenum sulfid (MoSg).

22. A detector of radiant energy of wave length shorter than that of the shortest Hertzian Waves comprising molybdenite.

23. An electron discharge device having an input circuit including an impedancevarying element and a circuit including a photo-sensitive cell inductively coupled to said input circuit.

24. The method of detecting the passage of an object across a given line which consists in castinga beam of invisible radiant energy along said line and observing the changes in said beam caused by the passage of said object. l I 25. In a signaling system, a source of nvisible radiant energy, means for controlling a beam of said energy in accordance withI signals and means for translating said signals comprising molybdenite.

WILLIAM W. co'BLENTZ. 

